Method for the prevention of corrosion



Patented Apr. 19, 1927.

UNITED STATES PATENT OFFICE.

STANLEY FOWLER,

or YORKSHIRE, AND EDWIN Ensnn, or LONDON, ENGLAND.

METHOD 35:03 THE PREVENTION OF CORROSION.

No Drawing. Original applicationfiled April 26, 1926, Serial No. 104,833, and inGreat Britain March 24,

- 1925. Divided and this application filed August 18, 1926. Serial No. 130,100.

This invention comprises improvements in or relating to methods for the prevention of corrosion.

free it can permanent be brought homogeneous 11111011 into complete and with 011, no

sedimentation occurring, and that corrosion of metallic surfaces canbe prevented very eifectiveh by applying to them a covering layer of this clear homogeneous the case to an equal we find is not liquid, which extent with other preparations of wool-fat in nonvolatile solvents.

According to the present invention therefore amethod of preventing corrosion of metallic surfaces consists in covering the surface with a substantially non-acid layer consisting essentially of anhydrous neutral soap-free wool-fat in homogeneous unclou ded admixture with a non-acid non-volatile thinning agent (for example a mineralhydrocarbon such as mineral-lubricating oil) The mixture of the pure neutral soap-free wool-fat and non-volatile thinning agent has moreover valuable cant and when used of machined bearmg-surventing corrosion faces prior to assembly of remove the unnecessary to properties as a lubrifor example for premachines, it is protective layer before the parts are brought into use. The lubricant itself is the subject of our co-pendin" United States patent application Ser.

N6. 104833 from which tion is a divisional.

A method of preparing of particular suitable state thepresent applicathe wool-fat in a after described. .It is to beunderstood that wool-fat as ordinarily purified does not yield an unclouded solution free from sediment and is therefore unsuitable for use according to this invention.

In one method of carrying the invention into effect, pure neutral soap-free wool-fat is mixed with pure neutral mineral lubricating oil. The proportion of mineral oil may vary according to the consistency o desired product.

ing; the molten purified oil while stirring. The mixture may reach 50 oil may be about amount of duct is desired,

f the is done by pourwool-fat into the temperature of the C. The amount of three or more times the Mixing wool-fat. If aless liquid pro-- less '-mineral .oil may be purity is hereinadded, or a thick mineral grease such as petroleum jelly may be used.

The composition is applied to articles which are to be protected from rust by any desired means, such as dipping, painting or spraying. It is found that the wool-fat imparts peculiar properties to the layer, rendering it strongly adherent notwithstanding the presence of the thinning agent so that it is not readily removed during handling, and yet the layer of the mixture is not gummy but possesses lubricating properties.

The wool-fat employed must be prepared in a way which renders it sufficiently neutral and soap-free and eliminates esters and other compounds which do not dissolve in mineral oils. One method is as follows The raw material is treated with alkali to efiect saponification of the fatty acids contained in it, saponification being effected in successive stages "with a quantity of alkali or the like in the initial stage or stages which is insufiicient to effect complete saponification and the soaps produced at each stage being removed before proceeding to the next stage of saponification. It is found that 'emulsification of the wool-fat in the alkali, and consequent loss, is thus reduced. Two, three. or evenfour stages of saponification may be employed;

For-example, crude wool-fat ofthe kind known as white concentrate (which sep; arates from wool-washing effluent and forms a scum on the surface thereon. when the effluent is allowed to stand) is run intoatank of boiling water at the rate of one and one half hundredweights of grease to gallons of water, which is preferably soft. This is boiled for ten minutes. Cold water is then added in sufiicien't amount (about ninetygallons). to reduce the temperature to 46 C. Assuming that the amount of fatty acid present is such that it would be neutralized by 22 ounces of sodium peroxide, twelve ounces of sodium peroxide are dissolved in 3 gallons of water and are added to the mixture with stirring. The whole is al lowed to stand for twelve hours. It is then boiled to, decompose any free sodium per oxide and to bring grease out of solution. It is allowed to settle and the aqueous portion is run off into acentrifugal machine, where the grease separates out and is returned to the original bulk.

The wool-fat (grease) is then washed by boiling with 150 gallons of water, allowed to settle and the aqueous portion centrifuged as. before. The centrifugally-separated wool-fat is again returned to the main bulk.

Into the grease is now mixedtwo-thirds of its bulk of water so as to be disseminated evenly therethrough. The temperature is adjusted to 46 C., and 10 ounces sodium peroxide are added, in solution as before, with stirring. This is allowed to stand for twelve hours, then diluted with 50 gallons ofwater and boiled. The aqueous portion only is decanted and centrifuged as before and the separatedgrease returned to bulk, which is again washed by boiling with water, the aqueous trifuged and t e recovered grease is returned to bulk. The product is the purified woolfat. Yorkshire brown grease can be purified in the same way, using of course a greater quantity of alkali in view of the greater quantity of contained acids. 7

The product is then mixed with neutral mineral lubricating oil as above described, and is found to produce .a clear solution free, from cloudiness and sediment. The purified Wool-fat yields less than 0.1% of ash and is therefore exceptionally free of soap, water and solid impurities and it contains less than 0.5% of fatty-acid. Ordinary neutralised wool-fat contains notable percentages of soaps, while in wool-fat where soaps are absent there is usually present an objectionable amount of fatty acid or other bodies which are insoluble in mineral oils.

' have found that for the purpose of our invention it is essential to use wool-fat which is 'quite neutral, anhydrous and soap-free,

if sedimentationis to be avoided on the one hand or injurious acid properties are to be ortion is decanted and cen-.

unclouded admixture with a non-acid non- 41. A method of preventing corrosion of 5 metallic surfaces which consists in covering the surface with a substantially non-acid layer consisting essentially of anhydrous neutral soap-free wool-fat in homogeneous volatile thinning agent.

2. A method of preventing corrosion of metallic surfaces which consists in covering the surface with a substantially non-acid layer consisting essentially of anhydrous neutral soap-free wool-fat in homogeneous unclouded admixture with a non-acid mineral-hydrocarbon.

A .method of preventing corrosion of metallic surfaces which consists in covering the surface with a substantially non-acid layer consisting essentially of anhydrous neutral soap-free woolfatin homogeneous unclouded admixture with a non-acid mineral-lubricating oil.

In testimony whereof we afiix our signatures.

STANLEY FOWLER. EDWIN EDSER. 

